-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi
if you work with PostGIS < 2.0 you can use the cleangeometry() function. http://www.kappasys.ch/pgtools/cleangeometry/cleanGeometry.sql Regards Horst Dr. Horst Düster Kappasys Alte Bernstrasse 13 CH-4500 Solothurn Tel.: +41 (0) 32 514 00 40 Mobil: +41 (0) 76 408 51 06 eMail: horst.dues...@kappasys.ch skype: horstduester Twitter: moazagotl Web: www.kappasys.ch lat: N 47° 12' 06.408" lon: E 7° 32' 13.740" Am 28.03.2012 12:29, schrieb Pavel Iacovlev: > Hello, > > Anyone has any ideas/tips of how to break lines at intersections ? > I have a a layer of lines and I want to break them at intersections > with them selfs, also (not that important but would be nice) break > lines forming a collapsed loop, for example 0.0;1.0;0.0 is broken at > 1.0. > > Currently this can be done in grass with v.clean tool=break,rmdupl but > it's relatively hard to add GRASS to a web app. > > So far I came up with this query and out of ideas right now: > > SELECT DISTINCT > gid, > ST_AsText(intersect_geom), > ST_Line_Locate_Point(GeometryN(the_geom, 1), intersect_geom) as point_loc1 > FROM > > (SELECT a.gid, ST_Intersection(a.the_geom, b.the_geom) AS > intersect_geom, a.the_geom > FROM roads as a, roads as b > WHERE ST_Intersects(a.the_geom, b.the_geom) AND (a.gid = 1) > ) AS res1 > > WHERE GeometryType(intersect_geom) = 'POINT' -- Need support for > MULTILINESTRINGS, take start and end point ? > ORDER BY point_loc1 > > which has the following result: http://jsfiddle.net/9RJ8a/ > I have the line, and the point positions on the line, but I can't get > around how to create my NEW broken lines with > ST_Line_Substring(geometry a_linestring, float startfraction, float > endfraction) > > Any suggestion of how to accomplished this ? is the approach correct ? > any other ideas ? > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJPcwSiAAoJENJq1wkKM7pS6NwH/3PzIeSfjG29wfrPx4mLu7gS 6gAYWk6Lsfp4kUEoy6uJdtGz6iFn3vY2blz1cA9diUrjw00O8m5/8IVFuI0jdyLM j6tzDbyB7jmXyF6F3TLKfnAakVGenhbcXTeHRL3ojAiKcq8UGsRDQYviQ3WZK9sY EXP9wJIunhawILOfFXEO68AcRDPLZcaLtZAE/qj4yY+p538M/8PNfuK2rBw6fcVO dPcug4wDewciPYQBcgKdbRpXtpfh9ytq4xYV16aAA8wVg4lFicldIm4cm8mytOrb 0bYYyFmAHtpBQ2Hv6A7eMxywzF8iQmu8oPl1I6ihPwol3VQ/Tws+nAKbfGKs3bs= =FgwT -----END PGP SIGNATURE----- _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
